Lamp base



FIG. 1 is a front perspective view of a lamp base showing my new design;

FIG. 2 is a front elevational view thereof on an enlarged scale, the sides and rear being identical thereto;

FIG. 3 is a top plan view thereof on an enlarged scale;

FIG. 4 is a bottom plan view thereof on an enlarged scale.

The standard is broken away in FIG. 2 for convenience of illustration. 

The ornamental design for a lamp base, as shown. 